A method for rounding and reconstructing a c-m large-angle sapphire crystal bar and a wafer product

Abstract

The application provides a C-bias-M large-angle sapphire crystal bar rounding reconstruction method and a wafer product, the method comprises the following steps: adopting a diamond sleeve drill to take a transition rough bar along a C-axis direction of a crystal ingot; accurately determining a C-axis and an M-axis direction vector through XRD and establishing a coordinate system; calculating a target normal vector in a C-M plane and processing a positioning reference surface; taking the positioning reference surface and an outer circle as clamping references to perform outer circle grinding, so that a new cylinder geometric axis is locked as 0°; and slicing at a 0° inclination angle to obtain a normal circle wafer. Through the conversion of a wafer bias angle into a crystal bar geometric inclination angle, the application realizes normal circle production under orthogonal slicing, and completely solves the problems of elliptical distortion and abnormal surface caused by a traditional oblique slicing process.

Description

Technical Field

[0001] This invention belongs to the technical field of sapphire single crystal processing, specifically relating to a method for rounding and reconstructing a C-biased M-angled sapphire crystal rod and a wafer product. Background Technology

[0002] Sapphire single crystals are widely used as a crucial substrate material for high-precision military devices due to their excellent optical, mechanical, and chemical properties. However, military devices have extremely stringent requirements for crystal orientation accuracy, typically within ±0.1°. For processing sapphire ingots with a large C-axis offset (6°~10°), the current industry practice is to address the offset during the slicing stage: using ordinary ingots with geometric axes parallel to the C-axis, and forcibly adjusting the angle using a tilting stage fixture on a multi-wire dicing machine. The target angled wafer is cut at an oblique angle.

[0003] However, the existing beveling solutions mentioned above have three fatal flaws: Defect 1: Geometric Distortion (Ellipticity Problem). When the angle between the slicing plane and the crystal rod axis is θ, the theoretical profile of the slice is an ellipse. For An elliptical wafer with a radius of 8° and a diameter of 100mm has a major axis a = D / cos8° ≈ 101.0mm and a minor axis b = 100mm. This type of elliptical wafer cannot be fitted with standard circular grinding discs, polishing pads, and lithography machine vacuum chucks.

[0004] Defect 2: Subsequent processing disaster (Warp exceeding limits). The non-circular shape causes severely uneven pressure distribution during grinding and polishing, resulting in excessive warp and surface volume (TTV), causing the entire batch to be scrapped and the yield to be extremely low.

[0005] Defect 3: Military-grade precision requirements cannot be met. Military-grade devices require crystal orientation accuracy within ±0.1°. Vibration and uneven stress from the beveling process can lead to microcracks and sub-surface damage, failing military reliability acceptance tests. Summary of the Invention

[0006] To address the aforementioned technical issues, this invention proposes a method for rounding and reconstructing sapphire crystal rods with large C-biased M-angles and a corresponding wafer product. This method eliminates the need for a tilted worktable during slicing, resulting in perfectly round wafers that completely resolve the "left-right elliptical" problem. The perfectly round wafer experiences uniform force during grinding and polishing, significantly reducing warpage and overall thickness deviation, meeting optical-grade polishing requirements. Simultaneously, it avoids edge chipping and subsurface damage caused by oblique cutting, satisfying the stringent requirements for material crystal integrity in military devices.

[0007] In a first aspect, the present invention provides the following technical solution: a method for rounding and reconstructing a C-biased M-angled sapphire crystal ingot, comprising: Step S1: Use a diamond drill bit to extract a cylindrical transition bar along the C-axis of the ingot to obtain a transition bar with a geometric axis approximately parallel to the C-axis. Step S2: Place the transition wool rod on an X-ray crystal orientation instrument, and accurately determine the actual spatial orientation of the C-axis direction vector and the M-axis direction vector by scanning the 0001 diffraction plane and the 1-100 diffraction plane, and establish a crystallographic coordinate system based on the actual spatial orientation; Step S3: Based on customer needs, C-biased M Calculate the normal vector of the target wafer surface in the CM crystallographic plane. Its angle with the C-axis is strictly equal to °; Adjust the spatial orientation of the transition bar on the orientation instrument so that a specific generatrix region of the transition bar is aligned. After the direction is locked, use a diamond grinding wheel to grind one end face of the transition bar to form a positioning reference surface; Step S4: Transfer the ground transition bar to a precision cylindrical grinding machine. Using both the positioning reference surface and the outer diameter of the bar as clamping references, fix the bar rotation angle using a special positioning block. °, so that the normal of the positioning reference surface is strictly oriented towards the direction of the spindle rotation axis; the feed grinding wheel performs external cylindrical grinding to remove the original eccentric outer circle until the outer diameter reaches the finished size D, obtaining the reconstructed crystal rod, so that the geometric axis of the reconstructed crystal rod is the same as the direction of the spindle rotation axis. Its angle with the C-axis is strictly locked at 1. ° and located within the CM plane; Step S5: Use the reconstructed ingot to perform orthogonal slicing on a multi-wire dicing machine, with the slicing feed direction perpendicular to the wire. The worktable tilt angle is set to 0° to directly obtain C-axis deviation M. A wafer product with a standard circular shape and a diameter of D.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention eliminates the need for a tilting worktable during slicing, and the sliced ​​wafers are perfectly round (with a circumferential diameter of D), completely solving the "left and right elliptical" problem and making it compatible with all standard wafer processing equipment; the round wafers are subjected to uniform force during grinding and polishing, significantly reducing warp (Warp < 10 μm) and total thickness deviation (TTV), meeting the requirements of optical-grade polishing; at the same time, it avoids edge chipping and sub-surface damage caused by oblique cutting, and the crystal orientation accuracy can be controlled within ±0.1°, meeting the stringent requirements of military devices for the integrity of material crystals.

[0009] Preferably, in step S1, the inner cylinder of the diamond drill bit... 106mm, rotation speed 2000rpm, feed rate 0.5-0.8mm, the diameter of the transition bar is larger than the diameter of the target finished product, and the difference between the diameter of the transition bar and the diameter of the target finished product is 3-5mm.

[0010] Preferably, in step S1, the angle between the direction of the scooping rod and the C-axis is within ±1°, and the cylindricity of the outer circle is ≤0.3mm.

[0011] Preferably, in step S2, the step of establishing a crystallographic coordinate system includes: taking the Z-axis of crystal growth as the C-axis, the plane perpendicular to the C-axis as the (0001) plane, measuring the normal of the (0001) plane as the C-axis vector Vc by XRD, measuring the normal of the (1-100) plane as the M-axis vector Vm, establishing a rectangular coordinate system O-XYZ, and aligning the Z-axis with Vc.

[0012] Preferably, in step S3, the target wafer surface normal vector The calculation formula is as follows: Let the unit vector of the C-axis be C=(0,0,1), and the unit vector of the M-axis be M=(1,0,0). Located in the CM plane, and making an angle with the C-axis. °, then .

[0013] Preferably, in step S3, the specific generatrix region is a straight line on the cylindrical surface of the transition bar. The physical shape of the transition bar revolves around the C-axis. By rotating the transition bar on the orientation instrument, a generatrix on the cylindrical surface of the transition bar is aligned with... direction.

[0014] Better It is ±0.1° or ±0.05°.

[0015] Preferably, in step S4, the grinding parameters are: 1500 mesh grinding wheel and 50 L / min flow rate.

[0016] Preferably, in step S4, the precision cylindrical grinding machine is an MG1420 precision cylindrical grinding machine; during clamping, a special positioning block is installed so that its precision side is in close contact with the positioning reference surface, and at the same time, a dial indicator is used to measure the outer diameter, and the center pin is adjusted so that the runout of the outer diameter of the grinding bar is ≤0.05mm. The rotation angle of the grinding bar is fixed with a positioning pin to ensure that the normal of the positioning reference surface strictly points to the spindle rotation axis.

[0017] Secondly, the present invention provides the following technical solution: a wafer product, which is prepared by the above-described method of rounding and reconstructing a large-angle sapphire crystal rod with a C-biased M-biased shape. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 A flowchart of the rounding and reconstruction method for a C-biased M-angled sapphire crystal rod provided in an embodiment of the present invention; Figure 2 A schematic diagram illustrating the crystallographic orientation and reference plane establishment principles provided in this embodiment of the invention; Figure 3 This is a schematic diagram of the rounding reconstruction clamping provided in an embodiment of the present invention; Figure 4 This is a comparison diagram of elliptic distortion between the method of this invention and the prior art method; Figure 5 This diagram compares the technical content of the method of the present invention with that of existing technologies.

[0020] The embodiments of the present invention will be further described below with reference to the accompanying drawings. Detailed Implementation

[0021] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain embodiments of the present invention, and should not be construed as limiting the present invention.

[0022] Example 1 In Embodiment 1 of the present invention, as Figure 1 As shown, a method for rounding and reconstructing a C-biased M-angled sapphire crystal ingot includes: Step S1: Use a diamond drill bit to extract a cylindrical transition bar along the C-axis of the ingot to obtain a transition bar with a geometric axis approximately parallel to the C-axis. Among them, the inner cylinder of the diamond drill bit. 106mm, rotation speed 2000rpm, feed rate 0.5-0.8mm, the diameter of the transition bar is larger than the diameter of the target finished product, the difference between the diameter of the transition bar and the diameter of the target finished product is 3-5mm, the angle between the bar-cutting direction and the C-axis is within ±1°, and the cylindricity of the outer circle is ≤0.3mm.

[0023] Specifically, a cylindrical transition blank with its geometric axis approximately parallel to the C-axis is obtained as the initial blank for subsequent processing. By using a diamond drill bit to hollow out the ingot along the C-axis, the hollow structure of the diamond drill bit forms a cylindrical blank, efficiently transforming the ingot material into a cylindrical shape suitable for subsequent external cylindrical grinding. The diameter is slightly larger than the target finished product diameter, reserving machining allowance for the subsequent rounding and reconstruction step, ensuring sufficient material for external cylindrical grinding and thus guaranteeing the accuracy of the final product's dimensions. This stage does not require crystal orientation accuracy, only ensuring the roundness of the outer shape, reducing the initial processing difficulty and cost, and improving processing efficiency. This step yields a transition blank with its geometric axis approximately parallel to the C-axis, providing a foundation for subsequent crystal orientation steps.

[0024] like Figure 2 As shown, in step S2, the transition wool rod is placed on an X-ray crystal orientation instrument, and the actual spatial orientation of the C-axis direction vector and the M-axis direction vector is accurately determined by scanning the 0001 diffraction plane and the 1-100 diffraction plane, and a crystallographic coordinate system is established based on the actual spatial orientation. The steps for establishing a crystallographic coordinate system include: taking the Z-axis of crystal growth as the C-axis, the plane perpendicular to the C-axis as the (0001) plane, measuring the normal of the (0001) plane as the C-axis vector Vc by XRD, measuring the normal of the (1-100) plane as the M-axis vector Vm, establishing a rectangular coordinate system O-XYZ, and aligning the Z-axis with Vc.

[0025] Specifically, a crystallographic coordinate system is established for the transition rod to provide accurate crystallographic data for calculating the normal vector of the target wafer face. Sapphire crystals exhibit anisotropy, and their C-axis and M-axis are key crystallographic indices that determine crystal orientation. By placing the transition rod on an X-ray crystallography instrument and using the principle of X-ray diffraction to scan the (0001) and (1-100) diffraction planes respectively, the actual spatial orientation of the C-axis and M-axis direction vectors can be accurately determined. That is, the actual orientation of the crystal's C-axis and M-axis in three-dimensional space can be accurately obtained, and a crystallographic coordinate system can be established accordingly. The accurate orientation in this step is the foundation for all subsequent steps. Only by accurately knowing the actual orientation of the C-axis and M-axis can the target normal vector be accurately calculated and precise angle control achieved, thereby ensuring that the crystal orientation accuracy of the final wafer product meets military-grade requirements (within ±0.1°).

[0026] Step S3: Based on customer needs, C-biased M Calculate the normal vector of the target wafer surface in the CM crystallographic plane. Its angle with the C-axis is strictly equal to °; Adjust the spatial orientation of the transition bar on the orientation instrument so that a specific generatrix region of the transition bar is aligned. After the direction is locked, use a diamond grinding wheel to grind one end face of the transition bar to form a positioning reference surface; Among them, the target wafer surface normal vector The calculation formula is as follows: Let the unit vector of the C-axis be C=(0,0,1), and the unit vector of the M-axis be M=(1,0,0). Located in the CM plane, and making an angle with the C-axis. °, then The specific generatrix region is defined as a straight line on the cylindrical surface of the transition bar. The physical shape of the transition bar revolves around the C-axis. By rotating the transition bar on the orientation instrument, a certain generatrix on the cylindrical surface of the transition bar is aligned with... direction.

[0027] Specifically, the generatrix refers to a straight line on the cylindrical surface. Because the bob originally grows along the C-axis, its physical shape revolves around the C-axis. The C-axis and the target direction have been measured. The angle between the two points. On the orientation instrument, the needle must be rotated at an angle so that a certain "genealogy" on the surface of the needle also points to the same point. Based on the measured angle between the C-axis and the actual physical axis, adjust the angle of the dividing head so that the specific generatrix on the surface of the bar is aligned with the direction of the bar. coincide.

[0028] After locking, use a diamond grinding wheel to grind one end face of the burr. The end face refers to the two circular planes of the cylinder (planes perpendicular to the original C-axis direction). Step S3 is to grind one end face so that the normal direction of this end face (the direction perpendicular to the plane) is equal to... Orientation. This end face is a dead reference used for positioning on the subsequent grinding machine. The measured crystal orientation value of this face is the final angle value of C-axis deviation (M). It forms a positioning reference surface, requiring the normal of this plane to be aligned with... The parallelism error is no greater than 0.05°.

[0029] Specifically, the crystal orientation angle required by the customer is transformed into a physical positioning reference surface, providing a precise clamping reference for subsequent rounding reconstruction. By converting the virtual target crystal orientation angle into a physical end face reference, a conversion bridge between "crystallographic direction and mechanical positioning reference" is established, enabling the cylindrical grinding machine to perform precise clamping and machining based on this reference. The normal of this positioning reference surface precisely corresponds to the normal of the target wafer surface, thus allowing the wafer orientation angle to be transformed into the crystal rod's geometric tilt angle in subsequent steps by reconstructing the geometric axis, laying the foundation for completely eliminating elliptical distortion.

[0030] like Figure 3 As shown, in step S4, the ground transition bar is transferred to a precision cylindrical grinding machine. Using both the positioning reference surface and the outer diameter of the bar as clamping references, a special positioning block is used to fix the bar's rotation angle. °, so that the normal of the positioning reference surface is strictly oriented towards the direction of the spindle rotation axis; the feed grinding wheel performs external cylindrical grinding to remove the original eccentric outer circle until the outer diameter reaches the finished size D, obtaining the reconstructed crystal rod, so that the geometric axis of the reconstructed crystal rod is the same as the direction of the spindle rotation axis. Its angle with the C-axis is strictly locked at 1. ° and located within the CM plane; in, For ±0.1° or ±0.05°, the machining parameters for grinding with a grinding wheel are: 1500 mesh grinding wheel, flow rate 50L / min. Machining error represents the allowable minute deviation between the actual axis and the target axis during machining (i.e., angular accuracy). In actual engineering, due to factors such as equipment precision and clamping errors, the actually machined axis cannot perfectly coincide with the theoretical vector. Therefore, the introduction To represent this controllable error range, this small deviation range ( This is a key indicator to ensure that subsequent "orthogonal slicing" can produce qualified products (such as those meeting military or optical-grade polishing requirements). It means that although there may be slight errors, these errors are strictly controlled within the allowable range, thereby ensuring that the various performance indicators of the wafer after slicing meet the standards.

[0031] The precision cylindrical grinding machine is an MG1420 precision cylindrical grinding machine. During clamping, a special positioning block is installed so that its precision side is in close contact with the positioning reference surface. At the same time, a dial indicator is used to measure the outer diameter, and the center is adjusted so that the runout of the outer diameter of the grinding bar is ≤0.05mm. The rotation angle of the grinding bar is fixed with a positioning pin to ensure that the normal of the positioning reference surface is strictly pointing to the spindle rotation axis.

[0032] Specifically, the geometric axis of the crystal ingot is reconstructed through external cylindrical grinding, transferring the crystallographic deviance to the geometric axis of the crystal ingot. The transition blank is then transferred to a precision external cylindrical grinding machine, using both the positioning datum surface machined in step S3 and the outer diameter of the crystal ingot as clamping datums. The positioning datum surface provides angular positioning, and the outer diameter provides radial positioning; the combination of these two achieves precise clamping with six degrees of freedom. A dedicated positioning block is used to fix the rotation angle of the blank, ensuring that the normal of the datum surface is strictly aligned with the direction of the spindle rotation axis, that is, ensuring that the rotation axis of the grinding machine spindle is aligned with the normal of the target wafer surface. The directions coincide. At this point, although there is a distance between the C-axis of the crystal inside the bar and the axis of rotation of the main shaft... The included angle, but the clamping posture has been precisely defined; The feed grinding wheel performs external cylindrical grinding to remove the original eccentric outer diameter. Since the spindle's axis of rotation is... The grinding wheel rotates around this axis to grind, and the material removed is relative to the direction. The eccentric portion of the axis. After grinding until the outer diameter reaches the finished size D, the surface of the newly formed cylinder is completely surrounded by... The rotational motion of the axis generates the geometric axis of the new cylinder, therefore the geometric axis of the new cylinder is... The angle between this geometric axis and the crystal's C-axis is strictly locked at [value missing]. And it is located within the CM plane. This step involves "clamping and positioning—around..." The process logic of "axis rotation - grinding shaping" reconstructs the original cylinder along the C-axis direction into a cylinder along the C-axis direction. The cylindrical shape of the crystal rod is aligned so that its geometric axis completely coincides with the normal of the target wafer surface, thereby converting the wafer's off-center angle into the crystal rod's geometric tilt angle. This reconstruction operation is the core of the entire invention and directly determines whether subsequent orthogonal slicing can yield a perfectly circular wafer.

[0033] Step S5: Use the reconstructed ingot to perform orthogonal slicing on a multi-wire dicing machine, with the slicing feed direction perpendicular to the wire. The worktable tilt angle is set to 0° to directly obtain C-axis deviation M. A wafer product with a standard circular shape and a diameter of D.

[0034] Specifically, a circular wafer is obtained through orthogonal dicing. The reconstructed ingot is then sliced ​​on a multi-wire dicing machine, since the geometric axes of the ingot have been reconstructed to correspond to the normals of the target wafer surface. The direction, i.e., the axis of the crystal rod coincides with the normal of the target wafer surface, is such that the tilt angle of the multi-wire dicing machine's table is set to 0°, making the dicing feed direction perpendicular to the rod axis. At this point, the cutting plane is perpendicular to the crystal rod axis. According to the geometric properties of a cylinder, the intersection of the cutting plane perpendicular to the axis and the cylinder is circular. Therefore, the resulting wafer is a perfect circle with a diameter equal to the crystal rod diameter D. Simultaneously, due to the crystal rod axis... The angle between the crystal and the C-axis is And it lies within the CM plane, therefore the normal of the cut wafer face is... The wafer is C-biased M ° Wafer. This step directly utilizes the geometric characteristics of the reconstructed crystal ingot to obtain a perfectly round wafer in one go under zero-tilt-angle orthogonal cutting mode, completely avoiding the elliptical distortion problem caused by the cutting plane not being perpendicular to the crystal ingot axis in traditional beveling processes.

[0035] In another embodiment of the present invention, a wafer product is also provided, which is prepared by the rounding and reconstruction method of C-biased M-large angle sapphire crystal rod as described in Embodiment 1.

[0036] To further illustrate the effects of this invention, the following uses a C-biased M8° sapphire crystal rod (target diameter) as required by the C military project. (100mm) Please explain: A diamond reaming sleeve is used to extract a diameter along the C-axis of the ingot. A 105mm transition bar (with a 2.5mm allowance on one side for subsequent rounding correction). The angle between the bar direction and the C-axis is controlled within ±1°, and the cylindricity of the outer circle is ≤0.3mm.

[0037] The transition rod was placed on an XRD crystal orientation instrument, and the diffraction peaks of the (0001) and (1-100) planes were scanned sequentially to accurately determine the projected coordinates of the C-axis on the end face and the direction of the M-axis. The actual direction vector of the C-axis was calculated, and its angle with the geometric axis of the rod was verified to be within ±1° (normal rod-scouring deviation). The target deflection angle was set. =8°, calculate the target normal vector in the C–M ​​plane. .

[0038] Adjust the indexing head of the orientation instrument, first rotating it around the bob axis to the positive direction of the M axis, then tilting it 8° to align the end face normal. After locking the worktable, use a diamond grinding wheel to grind the right end face of the burr flat to form a positioning reference surface.

[0039] Test results: The XRD instrument was used to re-measure the reference plane. The angle between the normal of the reference plane and the C-axis was 8.05°, which is located in the C–M ​​plane with a deviation of 0.05°, meeting the accuracy requirements.

[0040] Mount the transition bar onto the MG1420 precision cylindrical grinding machine. Install the special locating block, ensuring its precision side is tightly against the locating reference surface; simultaneously, use a dial indicator to check the outer diameter, and adjust the center to ensure the bar's outer diameter runout is ≤0.05mm. Fix the bar's rotation angle with locating pins, ensuring the reference surface normal strictly points to the spindle rotation axis.

[0041] Start the spindle rotation, feed the grinding wheel for rough grinding (feed rate 0.05mm / pass) and finish grinding (feed rate 0.01mm / pass), and circulate the grinding until the outer diameter reaches the specified value. 100.00mm, outer circle roundness ≤3μm. At this point, the original geometric eccentricity is completely eliminated, and the geometric axis of the new cylinder is... (C deviates from M8° direction).

[0042] Using a multi-wire EDM machine, the worktable tilt angle is set to 0°, and the feed direction is perpendicular to the axis of the finished crystal rod (i.e., perpendicular to the axis of the crystal rod). ), cut directly.

[0043] Product verification results: Wafer shape: perfectly round, diameter = 100.0 ± 0.05 mm, roundness ≤ 5 μm (compliant with standards); X-ray diffraction test: actual deflection angle = 8.03°, crystal orientation accuracy ±0.03°, far superior to the military requirement of ±0.1°; Edge quality: No chipping, subsurface damage layer depth ≤ 5μm; After CMP polishing: Warp < 10μm, TTV < 5μm, meeting the requirements of the lithography machine vacuum chuck; Next, the circular reconstruction method of the present invention is compared with the oblique cutting method provided in the prior art, and the results are as follows: Figure 4 , Figure 5 As shown, the existing oblique cutting method requires tilting the workpiece stage by 6°~10° during the slicing stage. The slicing plane is not perpendicular to the crystal rod axis, resulting in an elliptical wafer shape with the major axis exceeding the diameter by about 1%. This elliptical wafer cannot be adapted to standard wafer grinding pads, polishing pads, and lithography machine vacuum chucks, and must use custom fixtures, resulting in extremely low universality. At the same time, the elliptical shape causes severe uneven pressure distribution during subsequent grinding and polishing, resulting in a warp of ≥30μm that is prone to exceeding the standard, a high edge chipping rate, and a crystal orientation accuracy of only ±0.3°, which cannot meet the military-grade requirement of ±0.1°. In addition, vibration and uneven stress during the oblique cutting process cause microcracks and subsurface damage, making the entire wafer unable to pass military reliability acceptance. In contrast, this invention reconstructs the geometric axis of the crystal rod to the normal direction of the target wafer surface during the rounding stage, enabling subsequent slicing to adopt a 0° orthogonal cutting mode with the slicing surface perpendicular to the crystal rod axis, directly obtaining a perfectly round wafer (diameter = D), fundamentally eliminating elliptical distortion. The perfectly round shape ensures uniform force during grinding and polishing, reducing warp to below 10μm, significantly reducing edge chipping rate, and improving crystal orientation accuracy to ≤±0.05°, which is 6 times better than existing technologies. Furthermore, the wafer can be directly adapted to all standard wafer processing equipment, achieving universal processing, and ultimately greatly reducing subsurface damage, meeting the stringent reliability requirements of military devices for the integrity of material crystals.

[0044] The method for reconstructing the roundness of a C-biased M-angled sapphire crystal rod provided in Embodiment 1 of this invention eliminates the need for a tilted worktable during slicing, resulting in perfectly round wafers (with a circumferential diameter of D), completely resolving the "left and right elliptical" problem. This method is compatible with all standard wafer processing equipment. The round wafers experience uniform stress during grinding and polishing, significantly reducing warpage (Warp < 10 μm) and total thickness deviation (TTV), meeting optical-grade polishing requirements. Simultaneously, it avoids edge chipping and sub-surface damage caused by oblique cutting, and the crystal orientation accuracy can be controlled within ±0.1°, meeting the stringent requirements for material crystal integrity in military devices.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for rounding and reconstructing a C-biased, M-biased, large-angle sapphire crystal rod, characterized in that, include: Step S1: Use a diamond drill bit to extract a cylindrical transition bar along the C-axis of the ingot to obtain a transition bar with a geometric axis approximately parallel to the C-axis. Step S2: Place the transition wool rod on an X-ray crystal orientation instrument, and accurately determine the actual spatial orientation of the C-axis direction vector and the M-axis direction vector by scanning the 0001 diffraction plane and the 1-100 diffraction plane, and establish a crystallographic coordinate system based on the actual spatial orientation; Step S3: Based on customer needs, C-biased M Calculate the normal vector of the target wafer surface in the CM crystallographic plane. Its angle with the C-axis is strictly equal to °; Adjust the spatial orientation of the transition bar on the orientation instrument so that a specific generatrix region of the transition bar is aligned. After the direction is locked, use a diamond grinding wheel to grind one end face of the transition bar to form a positioning reference surface; Step S4: Transfer the ground transition bar to a precision cylindrical grinding machine. Using both the positioning reference surface and the outer diameter of the bar as clamping references, fix the bar rotation angle using a special positioning block. °, so that the normal of the positioning reference surface is strictly oriented towards the direction of the spindle rotation axis; the feed grinding wheel performs external cylindrical grinding to remove the original eccentric outer circle until the outer diameter reaches the finished size D, obtaining the reconstructed crystal rod, so that the geometric axis of the reconstructed crystal rod is the same as the direction of the spindle rotation axis. Its angle with the C-axis is strictly locked at 1. ° and located within the CM plane; Step S5: Use the reconstructed ingot to perform orthogonal slicing on a multi-wire dicing machine, with the slicing feed direction perpendicular to the wire. The worktable tilt angle is set to 0° to directly obtain C-axis deviation M. A wafer product with a standard circular shape and a diameter of D.

2. The method for rounding and reconstructing a large-angle C-biased M-biased sapphire crystal rod according to claim 1, characterized in that, In step S1, the inner cylinder of the diamond drill bit... 106mm, rotation speed 2000rpm, feed rate 0.5-0.8mm, the diameter of the transition bar is larger than the diameter of the target finished product, and the difference between the diameter of the transition bar and the diameter of the target finished product is 3-5mm.

3. The method for rounding and reconstructing a large-angle C-biased M-biased sapphire crystal rod according to claim 1, characterized in that, In step S1, the angle between the direction of the scooping rod and the C-axis is within ±1°, and the cylindricity of the outer circle is ≤0.3mm.

4. The method for rounding and reconstructing a large-angle sapphire crystal rod with a C-biased M-biased shape according to claim 1, characterized in that, In step S2, the steps of establishing a crystallographic coordinate system include: taking the Z-axis of crystal growth as the C-axis, the plane perpendicular to the C-axis as the (0001) plane, measuring the normal of the (0001) plane as the C-axis vector Vc by XRD, measuring the normal of the (1-100) plane as the M-axis vector Vm, establishing a rectangular coordinate system O-XYZ, and aligning the Z-axis with Vc.

5. The method for rounding and reconstructing a large-angle C-biased M-biased sapphire crystal rod according to claim 1, characterized in that, In step S3, the target wafer surface normal vector The calculation formula is as follows: Let the unit vector of the C-axis be C=(0,0,1), and the unit vector of the M-axis be M=(1,0,0). Located in the CM plane, and making an angle with the C-axis. °, then .

6. The method for rounding and reconstructing a large-angle sapphire crystal rod with a C-biased M-biased shape according to claim 1, characterized in that, In step S3, the specific generatrix region is specifically a straight line on the cylindrical surface of the transition bar. The physical shape of the transition bar revolves around the C-axis. By rotating the transition bar on the orientation instrument, a certain generatrix on the cylindrical surface of the transition bar is aligned with... direction.

7. The method for rounding and reconstructing a large-angle C-biased M-biased sapphire crystal rod according to claim 1, characterized in that, It is ±0.1° or ±0.05°.

8. The method for rounding and reconstructing a large-angle sapphire crystal rod with a C-biased M-biased shape according to claim 1, characterized in that, In step S4, the grinding parameters are as follows: 1500 mesh grinding wheel and 50 L / min flow rate.

9. The method for rounding and reconstructing a large-angle sapphire crystal rod with a C-biased M-biased shape according to claim 1, characterized in that, In step S4, the precision cylindrical grinding machine is an MG1420 precision cylindrical grinding machine. During clamping, a special positioning block is installed so that its precision side is in close contact with the positioning reference surface. At the same time, a dial indicator is used to measure the outer diameter, and the center is adjusted so that the runout of the outer diameter of the grinding bar is ≤0.05mm. The rotation angle of the grinding bar is fixed with a positioning pin to ensure that the normal of the positioning reference surface strictly points to the spindle rotation axis.

10. A wafer product, characterized in that, The wafer product is prepared using the rounding and reconstruction method of C-biased M-angled sapphire crystal rods as described in any one of claims 1-9.

Images